


Abzu

by halosaximus



Category: Marvel Cinematic Universe
Genre: Alien Planet, Aliens, Alternate Universe - Space, Future Fic, Interspecies Relationship(s), M/M, Mermaids, Mermen, Stephen's this weird kinda mermaid-alien thing, once you get past that it's pretty good I promise
Language: English
Status: Completed
Published: 2018-09-11
Updated: 2018-11-19
Packaged: 2019-07-11 07:08:56
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 8,095
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15967259
Author URL: https://archiveofourown.org/users/halosaximus/pseuds/halosaximus
Summary: For the first time during his lonesome research on an alien planet, Tony finds intelligent life in the form of a merman-like creature.





	1. To Know, Water

**Author's Note:**

> i originally posted this fic to tumblr, but i felt the need to put it here weeks later so ?????? feedback is greatly appreciated, and enjoy !!!!!!

Above the waves, a foreign sun nested among its own sea of blue, casting its morning rays upon an endless ocean. Beneath these waves, life was anew, for spring upon Abzu had come.

“Cycle 2, Sol 84,” His eyes, having once been wary and wide at new surroundings, now focused on individual targets in his path. He swam towards a fresh patch of Abzuian coral, out of easy reach yet not too far from home. “Fifth day of spring. This coral’s already unravelling at the Clarifian Reef. Not much change from Cycle 1. Stand-by.”

He powered down his seaglide and set it on the rocks as he made a soft landing, his scanners already pulling up statistics in his helmet. He reached into his pocket and slid a knife from its confines, checking twice to make sure it wasn’t his thermoblade. He wasn’t in the mood to cook his coral- he would much rather research it. He already tampered enough with this biome, with all his studying and the generous amount of construction he performed on his lab every now and again. 

He reached back and slid the coral effortlessly into his pack before grabbing his seaglide and bounding off. The system in his suit (handily connected to the main computer back at his base, as well) was still processing information, running checks down to the coral’s very DNA. He powered on the seaglide and started making his way home, the images and words displayed on his screen nothing but static. He’d look it over, but not until he ate something. It didn’t take FRIDAY to tell him that he hadn’t digested anything since his last meal nearly two days ago. He shouldn’t be out in the sea as it was.

As he swam home, gently kicking behind him as he let his seaglide do the heavy work, he passed many familiar faces- all of which were fish, of course. He hadn’t identified a single humanoid species on this planet (not yet, he reminded himself. There was always a chance he’d find one. He had the rest of his life on Abzu, anyway), so he found friends in the creatures of the reefs and the shallow seafloors. At one point, it proved difficult, however, so his system tagged each one he named. Some had been there since the day he’d arrived, some were more freshly hatched, some had disappeared without a trace. It was for the last reason he refused to grow sentimental for each individual creature. That, and there’s also the fact that they’re fish.

His home wasn’t hard to spot. It was silver, glinting in the light that passed through the ocean. It was easy to locate, so much that one of his old teammates had said it was dangerously visible, but all the large predators that could do the base harm lived deep within the sea. These waters were far too shallow for them to thrive. It was also large, sturdy and abundant in rooms, only some multipurpose. It was built along a slope with winding passageways spiralling down, rooms hanging off the edge and secured by large pillars leading to the seafloor. The only rooms in his base without such were the moonpools, in which held seven separate pods and a heavy-duty submarine for overnight expeditions. In the month he’d spent alone, none of those vehicles had been often used.

He swam to the entry chamber and opened the vault, swimming in and making sure the door was sealed behind. He and his team had quickly discovered that, if not sealed properly, water was bound to leak. He reached up with his free hand and pressed his body downwards to better plant his feet on the ground before using his seaglide to press the large button by the second chamber door and waited patiently as the water drained from the confined space.

With a heavy sigh, he finally stepped into his base and sealed the door behind him, setting his seaglide on a rack as he made quick work of stripping his suit and hanging it to dry. He took the contents of his bag and sorted them- materials got put in lockers by the door, while items that needed research done were given to the nearest bot to take to the labs. He slid into a pair of slippers and trudged on sore ankles to the kitchens. 

One look in the fridge, and it was decided. Cooked swatterfish. Again.

He prepared his food and filtered some water for drinking before plopping along to the processing room, sitting down at his chair with a sigh as he looked up at the main computer. It powered on immediately, pulling up unfinished projects and (probably) useless information harvested for research. He pulled up the latest message and sat back as he bit down on his meal, slumping in the large, all-too-comfy chair. 

He was met with the face of Peter, and smiled as the boy in the recording did the same with a wave ‘hello’. “Hey there, Mr. Stark! We’re on the edge of our Solar System right now, but we’ll probably be home by the time you get this message. We’ve been looking over all the data you’ve been sending us, and Captain Rogers wanted me to tell you again how brave your sacrifice was, staying behind and all.”

Tony bit the inside of his cheek, feeling tears behind his eyes and Peter’s smile faded just slightly on the screen. “I don’t think I’ll ever really understand why you wanted to stay, but everyone back on Earth thanks you for it. You always have the option to come back home, too.” Tony sniffed at the word. _Home_. He hadn’t realized just how much he’d considered ‘home’ to be his new base. He’d only been there for a cycle, after all. 

On the screen, a familiar face came into view, and Tony practically beamed when he saw Dr. Banner. The man smiled somewhat solemnly with a wave. “Hey there, Tones! We hope you’re doing okay, out there!” 

Another face came into view. It was Clint, his jaw still covered in shaving cream as he scrambled into the room. “Parker, where the _hell_ did you put my razor?!” Tony laughed as he felt his eyes grow wet, smiling before remembering to eat. On the screen, Peter and Clint shouted back and forth ( _“Why would I have your razor? I haven’t grown any hair on my face yet, man!” “Oh, like you’ll ever even grow facial hair, Parker!”_ ) before the rest of the team piled in, each interrupting Peter’s private message. 

Peter. Bruce. Clint. Natasha. Thor. Steve. They hadn’t changed a bit since they’d left for home a month prior. Sometimes, it felt like they were still with him at the base. It almost made him regret his choice to stay behind.

He couldn’t be exactly sure why he stayed behind. He knew there wasn’t much left for him on Earth, and he was also aware that his agency could use more research (would the rest of Tony’s lifetime be enough for them?), but his mind refused to settle on the obvious reasons. It instead focused on a voice- a gut feeling- that told him every day, when he woke up, when he worked, when he went back to sleep for the night- _something’s out there_. And he knew he may never find it, but he had a good thirty years left in him. Perhaps that would be enough time.

“Hey, Tony.” Natasha’s voice was soothing to the ear, his old memories of her resurfacing faster than he could push them back down into the water. “We miss you already, and so does Earth. They’ve already got a memorium in DC commemorating you for your work and sacrifice. None of us have a statue as big as yours- not even the captain.” 

Hearing his name, Steve bent down slightly, flashing his signature smile. Tony’s heart somehow dropped and warmed up concurrently at the sight of it. “You deserve it. We know your a selfless guy, but it’s the least they could do for you.” He gazed into the camera as if he saw Tony on the other side. “We really do miss you, Tony.”

The message ended not too long after. He spent his hours working, and sent that day’s logs and research back to Earth when night fell beyond the base. He barely slept, but in the meager time he was able, he dreamt of nothing but an endless blue.

~#~

“The hell is this, Dum-E?” Tony put his hand on his hip, the other vaguely gesturing to the strange, goo-like creature in the ‘Living Specimens That Won’t Eat Each Other’ tank. It reminded him of pudding (if pudding were a sandy gray hue with four tentacles and was precisely the size of his palm) and was among one of the most odd things he’d been given to research, seeing as how it didn’t have any eyes or a mouth on top of its head (which probably meant they were on its underside. Disgusting). “Do you just send out bots to find the creepiest shit you can locate on the seafloor?”

The bot made a low whirring noise and aimed its claw at the floor, and Tony sighed as he looked back at the tank. He had nearly been about to sit and start his research on this new specimen when FRIDAY buzzed in with an alert.

“Mr. Stark, I’ve detected a species of unknown origin outside the base.” Tony’s brows furrowed as the AI put a map on the screen, and he quickly found the dot referencing the creature. “It appears to be approximately 2.7 meters long, which doesn’t match any species currently in the database.”

He bit the inside of his cheek, taking one last look at the tank before heading to the door. It would have to wait. “I want all external lights on, FRIDAY. Get the cameras rolling, and fire up the base’s defences in case of a hostile threat.”

“Aye, sir.” He made his way down the halls, pulling up the same map on his wristband and locating the unknown creature. It seemed to have been not too far from the observatory, but when his scanners indicated that the external lights had gone on, it fled, but still remained in the dark where it couldn’t be seen. 

He made a quick decision- one he didn’t completely think through, but seemed obvious at the time. “FRIDAY, all external lights off. Have them at the ready, and keep those cameras rolling.” He stepped into the observatory- a round, glass ball with a single, clear walkway in the center and no beams beneath to support it. 

His eyes scanned his surroundings beyond the observatory, and while he thought he would find nothing in the pitch black void, he caught sight of something in the distance. It seemed to glow a faint white with an intricate pattern, and with the way it moved, he could tell that it was a tail, and was fairly lengthy, as well. If the creature was 2.7 meters long, he wouldn’t doubt it.

The creature stopped, its tail flicking just slightly. Tony felt its gaze pool into him, and he stared back with wide eyes. “FRIDAY,” He murmured softly as if any sudden movement could scare it away. “I want all lights in the base turned off except for the one in here. I don’t want it to have any distractions.”

The AI silently obeyed, and the room grew a tad darker as the light in the hall behind him powered off. He clenched his jaw and balled his fists in nervousness. It was precisely reasons like this that sparked his curiosity and fear of the ocean. It was exhilarating, but terrifying, all the same.

His predictions stood corrected as he saw the glowing begin to inch closer, slow and steady. This thing seemed to be just as afraid of him as he was of it with how cautious it appeared. As it grew closer still, he saw more and more of its body illuminating, until he could make out the entire expanse of its lengthy tail and bits of its torso. Everytime it paused, it sat up straight in the water as a human would, and Tony knew from there that this was no ordinary fish.

Tony stepped closer to the glass, squaring his shoulders and squinting his eyes. The creature couldn’t have been ten meters from the glass, now. Still, it continued its cautious pace, no more of it illuminated than it had been before. Hesitantly, Tony reached out to the glass, delicately placing his hand there. His eyes remained fixated on the same spot, his free hand quivering in anticipation. The creature paused before growing closer still, and Tony watched in awe as a trail of lights went aglow down its arms. 

A webbed hand, sharply clawed and deathly pale, was placed upon his own across the glass. Tony’s brows furrowed as he felt his heartbeat stop altogether before racing out of control. In the meager light, he could see the scales of the creature’s long, illuminated tail, stretching upwards past its muscled torso where a trail of glowing pieces traveled from its navel to its neck and branching outward onto its arms and hands. He was still unable to flesh out a head or the rest of its tail in the dark.

With a quivered breath, he rooted his feet into the ground. “FRIDAY,” He spoke softly, brushing his tongue over his lips. “External lights on.”

The AI did as she was told, and Tony came face-to-face with something out of a sci-fi film. The creature, stunned, pulled away from the glass, eyes wide but refusing to flee. Tony’s mouth fell agape as he took in all of the creature, glancing downwards to see its tail stretch even longer than he’d imagined, a flurry of dancing color with wild fins prancing around it and flourishing like bellowing skirts at its very bottom. The torso itself was pale yet structured much like a man’s, were it not for the fins on its outer-arms and all of the scales and oddly thin muscles that came with them. On its head, its cheekbones were prominent with piercing eyes and a crown of fins for hair- a lion’s mane. It’s ears were pointed and long, and in its mouth were subtly pointed teeth Tony was sure could tear his whole arm off. 

If Tony didn’t know any better, he’d say he was staring at a mermaid.

They both seemed just as entranced with each other, eyes searching for answers in the other’s exterior. Tony couldn’t get past the fact that this merman’s scales shined a dazzling rainbow in the light, blindingly beautiful. This creature was odd, a thing of myth and downright terrifying to see, but he’d be damned if he didn’t admit how gorgeously stunning it was.

He needed to get closer. 

His eyes searched the waters and found a nearby moonpool for a seapod a level below him and, testing the creature’s intelligence, he pointed to it. He made a sweeping gesture with his arm, diving under and up again, and the creature watched with awe before speeding off towards the aforementioned moonpool. Tony smirked to himself before he quickly sped from the observatory. _Smart fish_.

He opened the vault door to the moonpool and stepped inside, nothing in sight but the seapod connected to its hoists just slightly above the water. He crouched by the edge and gazed into the void, somehow not expecting the ‘merman’ to actually breach the surface (slowly- it was still cautious, as it should be). His eyes widened once more, as did the creature’s, and he found himself unconsciously leaning closer to the water.

Hesitantly, he placed a hand over his chest, unblinking. “My name is Tony.” The creature slid closer just slightly, placing its hand over its own chest. “Tony,” He gestured to himself, then to the creature. “And you?”

The creature patted its chest, referring to itself. In a low voice, it croaked, “Svent.” It made a soft click in its voice at the soft ‘e’, which he was sure was a vital element to its name. It pointed to Tony, then back to itself. “Town...Ton- Tony. Tony...Svent.” It appeared to be male from its baritone voice (at least, in human standards) and was clearly at his level of intelligence; he had a name, an awareness of himself, and he was sure the others of his kind were just the same. Not only that, but he was able to _adjust his vocal cords_ to a human tone of speaking within mere seconds just from hearing Tony’s voice. Was his entire body just as variable as his voice?

“Svent,” Tony repeated with a smile playing at his lips. “Can I call you _Stephen_?”

The creature thought for a moment before patting its chest. “Stev-” It tried again, forming the words. “Stephen?”

“Yes- Stephen.” Tony nodded, scooting closer on his knees just slightly. He let his back slump, feeling the air between them grow looser. It then came to his attention that he wasn’t sure where to go from there. What else could he ask that he could possibly show with gestures? His ability to speak in gestures was restrained as well, as many symbols were strictly humane, such as nodding or just a thumbs-up. This would be much harder than he first anticipated, he thought. 

Out of curiosity, he decided he would very much like to see more of him, and could most likely go from there. He shifted on his knees, feeling the steel beneath dig into them. He gestured to his thighs, clearing his throat. “Can I see your tail?” No reply. Tony instead moved to lay on his back and put his legs together in the air, moving them around. “Tail?”

Stephen’s eyes lit up as he nodded, moving to the edge of the pool and hoisting himself onto the platform. Tony watched in awe as his scales shimmered, much brighter than they had earlier in the water. His eyes scaled up the expanse of the creature’s body, then noticing the gills at his neck. His eyes widened as the slits there blended into pale skin, vanishing from sight. He’d been right about other variable body parts, then.

Tony scooted to the corner of the pool though was hesitant to move any further. He wasn’t sure what this creature considered to be ‘hostile’, but he knew for a fact that he didn’t want to find out. Stephen slid his tail up from the water like a wave, fins dripping yet flowing through the air. Were they used for speed? Agility? Or perhaps they were just for show, essential for mating? In any case, they only added to the dazzling display of color before him; a flurry of rainbow beamed from his scales, glittering and glistening, and Tony was sure he’d never seen anything so stunning. 

Stephen glanced at his own tail and frowned, however, before dropping it gently back into the water. He slid completely back into it, utterly upset, and submerged himself from his chin downward. The crown of fins fluttered like the lips of a huffing horse. Tony’s brows furrowed, trying to understand the situation. He had seemed fine one second, but fled back into the water the next…

Tony decided not to question it (as he couldn’t, anyway) and sat back once more, sliding his hands up his thighs. He and Stephen eyed each other curiously for a few brief moments before Tony spoke. “FRIDAY, you’re recording all this, right?”

“Of course, Mr. Stark.” Stephen seemed just slightly startled by the new voice, looking around the moonpool with wide eyes, but didn’t flee. 

“Run diagnostics, delve into Stephen’s language and mannerisms. I wanna know all I can about this guy. Oh, and get Dum-E in here with some raw fish.”

“An odd request, but as you wish, sir.” Tony rolled his eyes. If his AI advanced any further, she’d take dictatorial control of the entire base. 

Tony, while knowing Stephen had no chance of understanding him, began to speak in a low, gentle tone. “It’s a beautiful tail, I hope you know.” Stephen’s head rose a bit out of the water, eyeing him curiously. “You’re a beautiful being- a little strange, too, but that’s really to be expected of an alien, I guess…”

Stephen slid closer if only slightly, but Tony’s eyes watched the small waves in the water. “You’re the first intelligent species we’ve found on this planet, and even if we can’t really communicate all that much, it’s nice to know we can make the effort, at least.” He hadn’t realized Stephen was so close until webbed hands softly grasped the edge of the pool, directly next to where Tony’s calves were tucked beneath his thighs. The creature looked up at him with wide, black eyes, entranced. Tony thought for a moment, and concluded that he felt just the same.

A soft whirring behind him had Tony spinning around like a kid caught by their parents, and Dum-E extended a fish in his claw. He suddenly wondered how long the bot had been standing there.

Tony grabbed the fish by its tail, mindful of the scales, and extended it to Stephen in open palms. The creature looked at it, awestruck, before placing a webbed hand on his own chest in question. “Stephen?” He questioned, patting his chest.

Tony nodded in reply, smiling. “Yes, Stephen. You can have it.” 

His guest eyed it, mouth agape, before he suddenly shot his head up. He placed his hands on Tony’s thighs, patting somewhat excitedly. “Tony! Tony!” He exclaimed, baring his teeth in a smile before he shot back down under the water, leaving Tony aghast with a dead fish still in his hands.

“What…?” Tony searched the water, hoping Stephen would shoot back up out of the water, but to no avail. He sat back with a sigh, still holding that _damned_ fish.

“Sir, if I may,” FRIDAY inclined. “I reckon, from his body language, Stephen was glad to accept your gift, but may have gone off to get his own for you in return. I recommend waiting for him to come back.”

It was a far stretch, but FRIDAY was rarely ever wrong in her calculations. He replayed the scene in his mind, recalling how Stephen had beamed at the offering. He lit up like an excited puppy, quite practically. It was rather cute, even for an alien merman. 

Not ten minutes later, Stephen breached the surface of the water, the smile still painted onto his face. Tony jumped in surprise but came closer to the edge the very next moment, giving a smile of his own. “There you are, Stephen. I thought you’d gone forever.”

Stephen, now suddenly looking a bit anxious, rose his hands from the water. Within them was a small collection of various rocks and seashells, bright and vibrant with a plethora of hues and patterns. Tony flushed. Stephen managed to get him a way cooler gift in just ten minutes or so, and all he could offer was a damned fish.

“Thank you, Stephen,” Tony set his fish off to the side and extended his cupped hands, the creature gently dropping the soaked rocks and shells into them with care. He eyed them for a moment before he set them down as well, then offering the fish to him once more. This time, Stephen remained planted before him, taking the gift with kind.

Stephen thought for a moment before he looked up, questioning. “Thack- Thank- Thank you?” Tony nodded, smiling. “Thank you, Tony!”

Tony eyed him curiously as he plucked the scales expertly from the fish, letting them fall and sink into the water before tearing bits of meat and popping them into his mouth. His gaze fell on Stephen’s scales, and he decided to take another shot.

“Stephen?” He questioned, the other pausing to look up at him. He gestured to his thighs. “Tail?” Stephen thought for a moment before giving a hesitant look. “Please, tail?”

Stephen looked away for a brief moment of thought before giving Tony a final look of decision. He placed what remained of his fish in his mouth and hoisted himself back up onto the edge of the pool, this time directly to Tony’s left.

Tony was taken slightly aback at Stephen’s new position but refused to complain. He eyed the other’s tail as Stephen continued to feast, now somewhat bashful compared to his previous state of joy. He brought his head closer in curiosity, and found that he could practically see himself in the luminous reflection.

Tony reached out with a hesitant hand, and even as Stephen stilled, he made no move to stop him. Something inside him clicked into place, more and more about Stephen unravelling. “You don’t like your tail, do you?” He brushed the tips of his fingers gently against a patch of scales to find that they were meshed smoothly together, unlike the layered armor of many other fish, yet he could tell that Stephen’s hide was exceptionally tough. “Is it because of all this color? Or do you just not like the way it looks?”

Stephen dropped the skeleton of the fish into the water, most of the meat already devoured, and let his hands fall to his sides. He sat back, letting his host do as he pleased. “I think it’s beautiful.” Tony admitted, running his hand along one of the many fins attached to the tail. “If you’ve got any more friends that say differently, go ahead and sock em’ in the jaw, for me.”

Stephen reached out with a webbed hand to grab Tony’s with delicate precision, slowly lifting it to his eye. Stephen seemed to study each and every crease there, tracing each finger with his gaze in awe. He flushed again; he wasn’t sure anyone had ever looked at him like that, never with such genuine curiosity and interest.

Eventually, as the night bore on, Tony knew they couldn’t stay there forever, and bid Stephen farewell. He gave a joyous “goodbye, Tony!” in return, and Tony had motioned with his hands for Stephen to ‘come back’ before they parted ways.

For the first time since his crew had gone home without him, he felt truly happy.


	2. No Destinies Ordained

“Hey, Mr. Stark! We have really good news!” Peter was in his pajamas, breadcrumbs from his toast at the corners of his mouth, yet he looked wide awake with his bright grin. Tony couldn’t help but smile to himself at the sight. 

Clint suddenly stepped into view, dressed only in pajama pants hung low on his lips. “We’re coming back for another tour!”

Oh.

_Oh._

Oh, _God_.

“Clint!” Peter droned. “I was gonna tell him!” 

Steve joined the other two, looking more happy than Tony had ever seen him. He placed his hand on the back of Peter’s chair and the other loosely only hip. He hadn’t aged a day. “We made the decision about a week ago with the council. They were the ones who wanted us to come back, and we thought you could use a few extra hands- for a few more years, anyway.”

Tony suddenly heard a dull ringing in his ear. His stomach dropped yet threatened to spill simultaneously. 

_Stephen_.

He quickly paused the log and jumped from his seat, moving only as fast as his legs could carry him. He grabbed a pair of flippers along the way, his suit already present (it was practically a second skin, as of late) and nearly toppled over trying to get them on his feet as he went. 

His hand haphazardly slammed on the large button by a familiar room, and he wasted no time in diving into the pool within. Stephen, at the edge of the pool, whipped his tail beneath the surface in sudden shock.

“Tony?” 

He swam over to the Abzuian, resting his arms on the edge of the pool. His eyes briefly flew over the screen ahead displaying a lesson in Earthen culture. He instead held out his hands for Stephen to take, a gesture they had formed over the past year. 

He gathered his breath and his words before speaking, slow enough for Stephen to easily translate. “Do you remember when I told you about my old friends?”

“The other Earthlings?”

“Yes, the other Earthlings…” Tony huffed, gazing at the water between them. He bit his lip and looked up to face Stephen with a solemn expression. He swallowed in his throat. “They’re coming back to Abzu.”

Stephen paused in thought, but instead of raising an alarm, he only smiled at Tony. “Does this mean I can meet them?”

Tony’s chest dropped so low he swore it must have sank to the bottom of the pool. His hands gently squeezed Stephen’s webbed ones, and he shook his head sadly, feeling tears gather at the edge of his eyes. “You know I can’t let them know about you and your people. We’ve talked about this.”

Stephen gave him a broken glance, the gills at his neck fluttering in frustration as his webbed hands tightened around Tony’s. There was no anger in his eyes, only disappointment. 

“What if they kept me secret, like you did?” Stephen suggested, and Tony’s brow furrowed as he pulled himself closer to Stephen. His legs brushed lightly against Stephen’s tail, but he didn’t seem to mind. “They’re nice, like you. They won’t e...ex…” Stephen glanced bewildered at the water as he searched for the right word.

“Exploit you?”

Stephen looked up with a nod. “They won’t... _exploit_ me for gain.” 

This was only the second time they had mentioned it, the first being Tony’s crash-course explanation of human culture and just why he couldn’t let them know of Stephen’s existence. It made him feel just as ashamed as it had before, whether Stephen felt the same or not. Humans seemed so primitive compared to what Stephen had told him of his own kind, but the Abzuian was always quick to remind him that his people functioned more around survival tactics and less around their own development. 

They both knew that Tony’s old crewmates weren’t like the majority of Earthlings. Admiral Fury had chosen them for a reason- they were genuinely devoted to the exploration, not exploitation, of alien planets. Even still, he couldn’t risk it- not when so much was on the line.

“Stephen, I…” He looked to their clasped hands between them, biting his lip in thought. “I know you’ve wanted to meet them for a while, but...I couldn’t risk that. I couldn’t risk you.”

The Abzuian’s eyes widened, if only slightly so, and the crown of fins on his head subtly ruffled. He’d never seen those fins react in such a way, but now wasn’t the time to question it. Tony was sure Stephen was just as upset as he was.

Stephen made a low grumble in thought, teeth just barely visible from his mouth. Tony waited patiently; Abzuians grew irate somewhat easily, and as much as he’d learned, Stephen still hadn’t mastered the formation of sentences in English. 

“Can I talk to you, Tony?” He asked, looking up. “When your...friends arrive?”

He considered it before giving a light sigh. “If I can manage it...but my crew is very...attentive, you see. If I can find time, of course we can still talk.”

Stephen gave him a smile, one just nearly shy, and Tony found himself giving the same in return.

~#~

On the day of their arrival, Tony swept the base one last time to make sure he’d either hidden or burned all collections of data on the Abzuian race. He was eternally grateful for his past self, opting to record everything on paper rather than in the system. The few remaining documents he had were sealed away in a vault beneath his bed. With the complex system of locks and passcodes, he knew that there was no getting into it.

Stephen was as safe as he could be.

He dropped into the water from the nearest moonpool and began his descent towards the undocked submarine further down the hill. His eyes frantically scanned the water before they landed on Stephen, a fish in hand as his tail whipped gently beneath him. Tony didn’t have to see his face to know he was upset. 

He gave Stephen a sorrowful wave before he entered the submarine, waiting in the entry chamber for the water to drain before he made his way into the main hub the next level up. While the bottom tier of the sub was used for storage, the top controlled everything, from heating to docking a seapod to activating emergency systems. There were only five seats in the main hub, including the pilot’s chair, which would prove a bit difficult when having to carry six other people aboard. 

Reaching the main controls, wasted no time in doing a final check of the systems before starting the engines (with only slight difficulty, as it had been quite a while since he’d actually used the submarine). The engine batteries were fully charged with fresh ones in the battery port, the spare seapod was firmly docked, and FRIDAY didn’t alert him of any systems threatening to malfunction. Everything was set, it seemed to him. Still, he stood from his chair and bent over the controls to search below from the glass window, only to find that Stephen had already vanished. He sighed in discontent and seated himself once more.

As he began his trek through the ocean waters, he turned on the sonar systems, and was somewhat disappointed when the holographic map didn’t bring up any signs of Stephen trailing behind (despite Tony telling him specifically not to follow in fear of being seen). He quickly turned the system back off and focused on reaching the landing pad.

It took him just twenty minutes to reach his destination, docking the submarine in the moonpool there before exiting into the water below and breaching the calm surface. He was taken aback, however, when he saw his crew already standing there, some holding their luggage while others carried crates of supplies and equipment. He looked up at them with wide eyes, a heavy sensation churning in his stomach.

Oh. He’d turned his coms off a week ago.

“What the hell, Stark?” The captain was the first to speak after a prolonged silence, and Tony could only avert his eyes to the water. “We’ve been trying to get ahold of you for days, now!”

Peter didn’t seem to care, as he immediately dropped his things and dived into the water, throwing his arms around Tony and pulling him as close as physically possible. He froze, not from lack of contact but in a somewhat dazed state of shock. FRIDAY hadn’t even alerted him that they’d landed. 

With his breathing becoming steadily heavier in his helmet, he slowly reciprocated Peter’s embrace. He felt his eyes growing wet as the boy rambled to him. “Oh, God, Mr. Stark, I thought I’d never see you again! You’re okay, I knew you would be, it’s so good to see you, it’s so good to be back…”

Through the boy’s near-cries, he barely registered Steve still lecturing him from the edge of the pool. “I’ll have you know that the agency set off a red alert when you wouldn’t respond! We were ordered to get to base immediately to investigate; we left half of our belongings on the ship!”

He could only smile sadly to himself, biting his lip and digging the chin of his helmet into Peter’s shoulder as his arms wrapped tighter around him. He was grounded by the feeling of the boy’s suit beneath his thin gloves, and he couldn’t help but dig his fingers into it, just to reassure himself that it was real.

For a single, overwhelming moment, he knew he wouldn’t have had it any other way, but when Stephen wormed himself back into Tony’s head, he was reminded of the long years ahead- and all he would lose in that time.

~#~

It was no new concept to the crew that Tony had always preferred to scour the ocean at night, especially in the relatively safe area they had planted themselves in. So, when Steve did his last check of the base that night, he didn’t bother to question why Tony was sliding on his fins and grabbing his seaglide on his way into the entry vault. Tony knew he wouldn’t want to talk to him, anyhow, seeing as Steve was still upset at him about the coms.

He swam out into the night and activated the lights on his seaglide, scanning his surroundings. His heart skipped in joy when he saw the familiar flash of light on scales, and swiftly swam to meet Stephen by a shelf of coral. 

The Abzuian went to meet him and embraced him tightly as if they hadn’t seen each other in years. With how long it took his crew to unpack and settle in, it sure felt like it, at least. They both knew, however, that hugs like this would be much less frequent within the coming years. He would take all that he could get.

A long, pieced stripe down Stephen’s tail began to glow a soft gold, followed by an illumination of other scattered scales beside the stripe and a few on his largest fins. Tony smiled and waved in return. He didn’t know too much Abzuian aquatic yet, but a simple “hello” was among one of the first things he’d learned not too long after they’d met.

Stephen led him along to a familiar cave, pushing the large boulder out of the way with brute strength to allow Tony through. Without putting it back, they carried on, Tony leading himself through the narrow tunnels until he reached a wide opening. Through that was a lake, and he swam upwards until he breached air within the cavern.

They, both knowing that Stephen could see in the dark while Tony very well could not, quickly set to work in setting up lights on the bank. He gave himself time to rest, laying himself out on the rock with his legs still in the water. Stephen settled next to him and make quick work of removing Tony’s helmet, treating it as if it would crack like an egg when he set it off to the side.

“I forgot how tedious it is to have a crew.” He spoke, his voice near a whisper yet still echoing through the cavern. “I’m sorry it took me so long to come and see you.”

“I forgive you.” Stephen folded his arms on the ground and rested his head on it, his eyes scanning Tony’s features as they always did. “I ate another fish while I was waiting.”

“Gruddlefish?”

“No, swatterfish.”

“Ugh.” Stephen smiled in amusement, and Tony turned his head to face him. Sometimes he wished Stephen was capable of laughing, but his vocals were so drastic compared to his own. When he’d asked why he couldn’t just change them as he had the first time they’d met, Stephen had told him that he was capable of shifting them and altering their frequencies, but he couldn’t just alter them completely. Still, Stephen smiled whenever amused. Or happy. Or excited. Or anytime he wasn’t too sad.

Stephen just smiled a lot. He wondered how anyone could be capable of such constant joy, especially when he only had Tony for company. He wondered if Stephen ever got bored of him. He hoped he didn’t. He certainly didn’t get tired of Stephen, that was for sure.

“How is your crew?” He asked, moving to say on his side. The glinting of light upon his scales caught Tony’s eye, even after so many months of seeing it. The colors were never the same, and never the same intensity; his tail was its own enigma.

“Oh, they’re...adjusting. Trying to get used to underwater living again. I swear, Peter would have opened the vaults without his suit on if I hadn’t stopped him.” Stephen flashed his teeth in a smile. Seeing how sharp they were was still sometimes a bit of a scare, especially with the dim lighting they were in. “They’ll get used to it, though.”

Stephen looked as if he were about to say something when he suddenly snapped his head towards the water, and dove back in without a word. Tony sat up in alarm, but didn’t dare to enter the water after him. If Stephen was that on edge about a threat, he knew he shouldn’t even be entering that water again until it was clear.

From out of the depths shot a large figure, landing heavily on the rocky shore with a loud grunt. Tony’s eyes went wide when he realized it was one of his crew members- and from that body stature, he knew it could only be Peter. He quickly rushed to his side as Stephen slithered onto the bank, teeth bared with his crown of fins raised and convulsing wildly upon his head.

“Peter, what the hell-” He removed Peter’s helmet and cast it aside, taking the boy’s head in his hands. Peter looked up at him, eyes wide, his entire body shaking.

“M-Mr. Stark, what the hell was that thing?” Stephen, realizing that Peter wasn’t a threat, immediately found the boy’s other side, causing the boy to go back into panic. He began thrashing and swearing, and Tony was forced to pin him by the shoulders. Stephen looked somewhat offended by the gesture.

“Stop- kid, _stop_.” Peter’s actions ceased but his breath still steamed on the glass of his helmet, his eyes wide and transfixed on Stephen, who now was slowly sinking back into the water with his gaze downcast. Tony wanted to tell Stephen to stay where he was, and not feel frightened or regretful, but he could tell that his friend had done a number on Peter’s wellbeing. “That’s just Stephen. He’s nothing to be afraid of.”

Tony slowly let go of his shoulders, and Peter’s first reaction was to sit up and slide further away from the water, hissing at the slight pain as he went. All that he could see in the water was Stephen’s head, his crown ruffling penitently. After a few moments of silence, he knew that the heavy air floating about wouldn’t cease to settle with their current state.

“He acted off of instinct. His people are just built that way. He’s sorry, I promise. He just...doesn’t know what to do, right now.” Peter’s eyes were trained on Stephen’s, just daring the Abzuian to make a move. It brought a sick feeling to Tony’s stomach. This was exactly why he didn’t want anyone from the crew to meet Stephen. “We’ve never really gone over that, I guess.”

“I don’t- I don’t understand,” Peter’s shoulders slumped, his voice shivering and cracked. “What is he?”

Tony’s jaw clenched, and his eyes began to grow wet as he looked to Stephen. His closest colleague, his best friend, his son, saw Stephen as nothing more than any other beast on Abzu. Did Peter think, that just from their first encounter minutes ago, that Stephen was just as ferocious and horrifying as what dwelled in the depths?

“His name is Stephen,” Tony began. “An Abzuian, as I’ve come to call them...the most intelligent species humanity has discovered, surpassing even our own minds.” Stephen looked up at him with wide eyes, inching closer. Tony turned his body just slightly towards him- an invitation. “Their calls can be heard from over two hundred miles away underwater, and various scales on their tail illuminate in order to communicate when verbal speaking isn’t available.”

Peter, though seemingly less frightened, still kept his eyes trained on Stephen, just daring him to make a move. Stephen bore a solemn expression of regret, but held his tongue. “Stephen’s been through a lot, kid. You just gotta know that he’ll pounce at the slightest threat, and that you absolutely cannot speak a single word of this to the crew. You understand?” 

Peter gave him a questioning glance, but his eyes once more quickly befell the Abzuian. “I-I don’t understand, Mr. Stark- why didn’t you alert home? This is the scientific breakthrough they’ve been looking for for a whole century-”

“You saw what happened to our home, Peter.” Peter now gave his full attention to Tony, his jaw going slack. Stephen’s ears perked in interest. “You’ve seen the pictures of what it was like before. Green, as far as the eye could see- where is that, now?”

Peter swallowed in his throat, bringing his legs to his chest. “Gone.”

Tony let out a quivered breath, his hand gently falling on Stephen’s scaled shoulder. “This planet is sacred, Peter. And if we were to give the agencies back home even the slightest spark of interest, they’ll see it as an inferno just begging to be put out. It’s almost like this world has a heart- it doesn’t deserve to turn into another Earth. The _people_ here don’t deserve it.”

Peter reached up to remove his helmet and held it before himself, gazing down at it with a sense of melancholy. “ _Please_ , Pete. Think about all the life you’d be putting at risk.”

This time, when Peter looked to Stephen, it was instead with a look of sorrow, and he could only watch as the boy’s eyes grew wet. The two only gazed at each other for a few moments before Peter spoke. 

“I’m sorry,” He began. “for freaking out. I mean, I didn’t really know what was going on- it was just kinda natural- but I’m sorry, anyway. And I don’t want your planet to be invaded by Earthlings, Mr. Stephen, I promise. I won’t let that happen.”

Stephen’s mouth went slightly agape as he translated Peter’s words. His eyes went wide when he realized what he’d said. “I am sorry, Peter, for…” Stephen grumbled in his throat as he searched for words, so Tony finished them for him.

“For mistaking him for another Abzuian and throwing him onto the shoreline?”

“Yes- yes. I am sorry.” Stephen apologized. “ _Very_ sorry.” 

“What- what’s that about? The whole “other Abzuian thing?” Peter looked to Tony for answers. “Where are all the others?”

Tony gave a sigh, running his wet glove through his hair. Stephen placed a hand on his thigh, giving him a pleading look. He knew almost immediately what it meant. 

“He doesn’t want me talking about it.” Tony replied. Peter’s face fell. 

“Later,” Stephen said. When ready- when I am ready.” Stephen finished. Tony gave him a sad smile. “I _think_.”

“You’ll be ready, I’m sure of it.” Tony placed his hand over Stephen’s in a comforting gesture. Peter gave them an odd look. Tony didn’t mind.

~#~

“Where have you two been?” Steve was at the hatch the moment they stepped through, arms crossed with a stern look on his face. “FRIDAY said you’d both left two hours ago, in the dead of night, on an _alien planet_. When we go for night missions, the whole team goes together-”

“With all due respect, I told him to come with, Cap.” Tony peeled off his glove and clapped Steve on the shoulder as he walked to the racks. He began to strip from his suit, and Peter wasn’t too far behind. “I couldn’t sleep, and I wanted to fix one of the modules in the seapod, and I’d supposed I’d need someone with me.” 

“Is this true, Parker?” 

“Yes, Captain.” Not a beat too late. A true ally.

Steve sighed, uncrossing his arms and making his way down the hall. “Be ready by sunrise. We’re all going on our first local dive tomorrow, and I don’t want anyone a second late,” He called, turning the corner.

“Yes, Captain.” Tony called back, followed by a sigh. He hung up his suit and slipped into his normal footwear. He and Peter retired for the night, bidding each other their silent goodbyes. 

And as he opened the safe that night, pouring over the data he’d collected with Stephen close in mind and even closer at heart, he knew Stephen would be just fine, so long as they had each other.

And maybe, they could have Peter there with them, too.

**Notes for the Chapter:**

> ok so i originally was just gonna leave this at the first part, but a few of you asked for more, and it only took me a month to do that lmao but anyway, this second part is named after a song from the actual Abzu soundtrack, and its a super pretty song on a SUPER PRETTY ALBUM so i recommend just going and listening to the entire thing, especially when you read scenes like the very first scene from the first part. i also renamed the first part after one of the songs, just an fyi
> 
> im not sure if i want to continue this, but if yall want to read more, just let me know and i'll think about it! for now, im gonna keep this marked as completed again, just a forewarning.


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